#include<iostream>
#include<string>

using namespace std;

int main(){
	string s, res;
	cin>>s;
	for(int i=0;i<s.size();i++){
		if(s[i]>='A'&&s[i]<='Z'){
			s[i] += 'a'-'A';
		}
		
		if(s[i]>='a'&&s[i]<='z'){
			res.push_back(s[i]);
		}
	}
	cout<<res;
}
